TWI574931B - High infrared transmission glass sheet - Google Patents

Description

High infrared transmission glass

The present invention relates to a glass sheet having high infrared transmission.

The invention also relates to the use of such glass sheets in devices that use infrared radiation that propagates primarily within the sheet.

Since the glass sheet according to the invention has high infrared (IR) transmission, it can actually be advantageously used, for example, to use optical techniques called plane scattering detection (PSD) or frustrated total internal reflection (FTIR) (or any Other techniques that require high infrared transmission are to detect the position of one or more objects (such as a finger or stylus) on the surface of the sheet in a touch screen or touch panel or trackpad.

Accordingly, the present invention is also directed to a touch screen, touch panel or trackpad comprising such a glass sheet.

PSD and FTIR technologies allow for multiple detection touch screens/panels that are inexpensive and can have relatively large touch-sensitive surfaces (eg, 3 to 100 inches) while also having a small thickness.

The two techniques include: (i) from one or more edges/sides, for example by means of LEDs emitting infrared radiation (IR) into the infrared transparent substrate; (ii) by means of total internal reflection optical phenomena (no radiation "away" The substrate), the infrared radiation propagates inside the substrate (which thus acts as a waveguide); (iii) the surface of the substrate is brought into contact with any object, such as a finger or a stylus, Local interference is caused by the diffusion of radiation in all directions; a portion of the deviation from the ray will thereby be able to "leave" the substrate.

In FTIR technology, the off-radiation forms an infrared spot on the inner surface of the substrate opposite the touch-sensitive surface. These off-beams are visible by a special camera located below the device.

The PSD technology itself contains two additional steps in the list of steps (i)-(iii): (iv) analyzing the resulting infrared radiation at the level of the edge of the substrate by a detector; (v) Calculate the position of the object in contact with the surface by the algorithm from the detected radiation. This technique is disclosed in particular in document US 2013/021300 A1.

Basically, glass is a material selected for use in touch panels due to its mechanical properties, durability, scratch resistance, optical clarity, and because it can be chemically or thermally toughened.

For glass panels having a very large surface area and therefore a relatively large length/width for PSD or FTIR technology, the optical path of the emitted infrared radiation is longer. In this case, the absorption of infrared radiation through the glass material thus has a significant effect on the sensitivity of the touch panel, which can then unduly reduce the length/width of the panel. In the case of glass panels having a relatively small surface area and thus emitting infrared radiation having a shorter optical path for PSD or FTIR technology, the absorption of infrared radiation through the glass material also has an effect on the energy consumption of the device in which the glass panel is integrated. .

Therefore, in this case a glass sheet that is extremely transparent to infrared radiation is very useful in order to ensure that the sensitivity on the entire touch-sensitive surface is not reduced or sufficient when the surface is large. In particular, glass sheets having the lowest possible absorption coefficient at the 1050 nm wavelength typically used in such techniques are desirable.

In order to obtain high infrared transmission (and visible light transmission), it is known to reduce the total iron content in the glass (represented by Fe ₂ O ₃ according to standard practice in the field) to obtain low iron glass. The citrate-based glass always contains iron as this is present as an impurity in many of the raw materials used (and especially in the sand). Iron exists in the structure of the glass in the form of ferric ion Fe ³⁺ and divalent iron ion Fe ²⁺ . The presence of ferric iron Fe ³⁺ makes the absorption of low-wavelength visible light weaker in the glass and stronger in the near-ultraviolet light (the absorption band is centered at 380 nm), while the divalent iron ion Fe ²⁺ (sometimes expressed as oxidation) The presence of the substance FeO) causes a strong absorption in the near-infrared rays (the absorption band is centered at 1050 nm). Thus, increasing the total iron content (in both forms) enhances absorption in visible and infrared light. In addition, the high concentration of the divalent iron ion Fe ²⁺ causes a decrease in the transmission of infrared rays (especially near infrared rays). However, in order to obtain an absorption coefficient at a wavelength of 1050 nm which is sufficiently low for touch-sensitive applications by only exerting an influence on the total iron content, the total iron content will be required to be significantly lowered, and thus (i) it will be generated too high. Production costs, because extremely pure raw materials are required (even if they are sometimes not present in a sufficiently pure state), (ii) or this will cause production problems (especially premature wear of the furnace and/or heating of the glass in the furnace) difficult).

In order to further increase the transmission of the glass, it is also known to oxidize the iron present in the glass, that is, to reduce the content of divalent iron ions to increase the content of ferric ions. According to their degree of oxidation of the glass redox specified, defined as Fe ²⁺ relative to the total weight of iron atoms present in the glass in the atomic weight ratio, i.e., Fe ²⁺ / total Fe.

In order to reduce the redox effect of the glass, it is known to add an oxidizing component to the batch of the raw material. However, most of the known oxidants (sulfates, nitrates, etc.) do not have sufficiently high oxidizing power to obtain the infrared transmission values sought by touch panel applications using FTIR or PSD technology, or must add too much. The oxidant is accompanied by disadvantages such as cost, coloring, and incompatibility with the production process.

It is an object of the present invention, in at least one embodiment thereof, to provide a glass sheet having high infrared transmission. In particular, it is an object of the present invention to provide a glass sheet having high near infrared radiation transmission.

The object of the invention is in at least one embodiment thereof to provide a glass sheet having a high infrared transmission, in particular in a device using infrared radiation mainly propagating inside the sheet.

Another object of the present invention, in at least one embodiment thereof, is to provide a glass sheet that is not caused when used as a touch-sensitive surface in a touch screen, touch panel or touch panel having a larger size. Any loss of sensitivity to touch-sensitive functions, or even loss, is minimal.

Another object of the present invention is, in at least one embodiment thereof, to provide a glass sheet for use as a touch sensitive surface in a touch screen, touch panel or touch panel having a more moderate size. Energy consumption is beneficial.

Another object of the present invention, in at least one embodiment thereof, is to provide a glass sheet having high infrared transmission and having an aesthetic appearance that is acceptable for the selected application.

Finally, it is also an object of the present invention to provide a glass sheet which is inexpensive to produce with high infrared transmission.

The present invention relates to a glass sheet having a composition comprising the following materials, the contents of which are expressed as a percentage of the total weight of the glass:

0.002 Total iron (expressed as Fe ₂ O ₃ ) 0.06%.

According to a particular embodiment, the composition additionally comprises, for example, 0.0001% Cr ₂ O ₃ 0.06% of the chromium content expressed as a percentage of the total weight of the glass.

Thus, the present invention is based on a completely novel and inventive method as it solves the proposed technical problems. In fact, the inventors have surprisingly shown that it is possible to combine low levels of iron in a glass composition with chromium in a specific range (particularly referred to as a strong colorant in so-called "selective" colored glass). To obtain a glass sheet that is highly infrared transparent and has an aesthetic appearance and that the color is not excessively adversely affected.

Throughout this document, all ranges and sub-field values within the range of values are expressly included as indicated, as the Also, unless explicitly mentioned, throughout the text, the percentage content is a weight value expressed relative to the total weight of the glass.

Other features and advantages of the present invention will become apparent after reading the following embodiments.

In the sense of the present invention, it is understood that glass means a completely amorphous material, and thus even excludes any crystalline material (e.g., such as vitro crystalline or glass ceramic materials) to some extent.

The glass sheet according to the present invention may be a glass sheet obtained by a float process, a draw process or a lamination process or any other known process for producing a glass piece from a molten glass composition.

According to the present invention, different raw materials containing chromium can be used to introduce chromium into the glass composition. In particular, chromium oxide, CrO, Cr ₂ O ₃ , CrO ₂ or CrO ₃ are possible and relatively pure sources of chromium. Other chromium-rich materials such as chromate, chromite and any other chromium-based compounds can also be used. However, compounds containing 6+ forms of chromium are less desirable for safety reasons.

The glass sheets according to the present invention can have a variety of and relatively large sizes. For example, it may have a range of up to 3.21m x 6m or 3.21m x 5.50m or 3.21m x 5.10m or 3.21m x 4.50m (referred to as PLF glass flakes) or for example 3.21m x 2.55m or 3.21m ×2.25m (referred to as the size of the DLF glass sheet).

The glass sheet according to the invention may have a thickness in the range between 0.05 mm and 25 mm. Advantageously, in the case of touch panel applications, the glass sheets according to the invention may have a thickness that varies between 0.1 mm and 6 mm. For touch panel applications, the thickness of the glass sheet according to the present invention is preferably from 0.1 mm to 2.2 mm for weight reasons.

According to the invention, the composition of the invention has such as 0.002 Total iron (expressed as Fe ₂ O ₃ ) 0.06% of total iron content. The total iron content (expressed as Fe ₂ O ₃ ) of less than or equal to 0.06% by weight can further increase the infrared transmission of the glass sheet. The minimum value means that the cost of the glass will not be excessively unfavorable because such low iron values usually require expensive, very pure raw materials or purification of the raw materials. Preferably, the composition has a total iron content (expressed as Fe ₂ O ₃ ) in the range of 0.002% to 0.04% by weight relative to the total weight of the glass. Particularly preferably, the composition has a total iron content (expressed as Fe ₂ O ₃ ) in the range of 0.002% to 0.02% by weight relative to the total weight of the glass.

According to a particularly advantageous embodiment of the invention, the composition has, for example, 0.0005% Cr ₂ O ₃ 0.06% chromium content. Particularly preferably, the composition of the invention has such as 0.001% Cr ₂ O ₃ 0.06% chromium content. Even more preferably, the composition of the invention has, for example, 0.002% Cr ₂ O ₃ 0.06% chromium content. The minimum value of such chromium content can further increase infrared transmission.

According to an advantageous embodiment of the invention, the composition has a chromium content (expressed in the form of Cr ₂ O ₃ ) such as: 0.0001% Cr ₂ O ₃ 0.03%, or even better, such as 0.001% Cr ₂ O ₃ 0.03%, and preferably, such as 0.002% Cr ₂ O ₃ 0.03%. These chromium content ranges enable significant transmission of infrared light and the aesthetic appearance of the glass sheet is not adversely affected. Even more preferably, the composition of the invention has a chromium content such as: 0.0001% Cr ₂ O ₃ 0.02%, or even better, such as 0.001% Cr ₂ O ₃ 0.02%, and preferably, such as 0.002% Cr ₂ O ₃ 0.02%.

According to another embodiment of the invention, the composition has such as 55 SiO ₂ 78% of the SiO ₂ content expressed as a percentage of the total weight of the glass.

According to another embodiment of the invention that can be considered in combination with the foregoing embodiments, the composition has such as 0 Al ₂ O ₃ 18% of the Al ₂ O ₃ content expressed as a percentage of the total weight of the glass.

According to another embodiment of the invention, the composition has a Fe ²⁺ content (expressed as FeO) of less than 20 ppm. Preferably, the composition has a Fe ²⁺ content (expressed as FeO) of less than 10 ppm. Particularly preferably, the composition has a Fe ²⁺ content (expressed in the form of FeO) of less than 5 ppm.

According to the invention, the glass sheet has a high infrared transmission. More specifically, the glass sheets of the present invention have high near infrared radiation transmission. In order to quantify the high transmission of the glass in the infrared range, the absorption coefficient at a wavelength of 1050 nm will be used in the present invention, so it should be as low as possible in order to obtain high transmission. The absorption coefficient is defined by the ratio between the absorbance and the length of the optical path covered by electromagnetic radiation in a given medium. It is represented by m ^-1 . It is therefore independent of the material thickness, but it depends on the wavelength of the absorbed radiation and the chemical nature of the material.

In the case of glass, the absorption coefficient ( μ ) at the selected wavelength λ can be calculated from the measured value of the transmission ( T ) and the refractive index n of the material ( thick = thickness), where the values of n, ρ and T are selected The wavelength λ changes:

Where ρ=(n-1) ² /(n+1) ² .

Advantageously, the glass sheet according to the invention has an absorption coefficient of less than or equal to 5 m ^-1 at a wavelength of 1050 nm. Preferably, the glass sheet according to the present invention has an absorption coefficient of less than or equal to 3.5 m ^-1 at a wavelength of 1050 nm. Particularly preferably, the glass sheet according to the invention has an absorption coefficient of less than or equal to 2 m ^-1 at a wavelength of 1050 nm. Even more preferably, the glass sheet according to the present invention has an absorption coefficient of less than or equal to 1 m ^-1 at a wavelength of 1050 nm.

Advantageously, the glass sheet according to the invention has an absorption coefficient of less than or equal to 5 m ^-1 at a wavelength of 950 nm. Preferably, the glass sheet according to the present invention has an absorption coefficient of less than or equal to 3.5 m ^-1 at a wavelength of 950 nm. Particularly preferably, the glass sheet according to the invention has an absorption coefficient of less than or equal to 2 m ^-1 at a wavelength of 950 nm. Even more preferably, the glass sheet according to the present invention has an absorption coefficient of less than or equal to 1 m ^-1 at a wavelength of 950 nm.

Advantageously, the glass sheet according to the invention has an absorption coefficient of less than or equal to 5 m ^-1 at a wavelength of 850 nm. Preferably, the glass sheet according to the present invention has an absorption coefficient of less than or equal to 3.5 m ^-1 at a wavelength of 850 nm. Particularly preferably, the glass sheet according to the invention has an absorption coefficient of less than or equal to 2 m ^-1 at a wavelength of 850 nm. Even more preferably, the glass sheet according to the invention has an absorption coefficient of less than or equal to 1 m ^-1 at a wavelength of 850 nm.

According to an embodiment of the present invention, in addition to the impurities specifically included in the raw material, the composition of the glass sheet may further comprise a smaller proportion of additives (such as reagents for helping the glass to be melted or refined) or fire resistant to form a melting furnace. The element produced by the dissolution of the material.

In accordance with an embodiment of the present invention, the composition of the glass sheet may additionally comprise one or more colorants adjusted in amount depending on the effect sought. This (these) colorants can be used, for example, to "neutralize" the color produced by the presence of chromium, and thus make the color of the glass of the present invention more neutral and colorless. Alternatively, this (these) colorant can be used to obtain the desired color in addition to the color produced by the presence of chromium.

According to another advantageous embodiment of the invention which can be combined with the preceding embodiments, the glass sheet can be coated with a layer or film (for example a colored PVB film) which is capable of changing or neutralizing the color which can be produced by the presence of chromium .

The glass flakes according to the invention can advantageously be toughened chemically or thermally.

According to an embodiment of the invention, the glass sheet is coated with at least one transparent conductive layer. The transparent conductive thin layer according to the present invention may be, for example, a layer based on SnO ₂ :F, SnO ₂ :Sb or ITO (indium tin oxide), ZnO:Al or ZnO:Ga.

According to a further advantageous embodiment of the invention, the glass sheet is coated with at least one anti-reflective (or anti-glare) layer. This embodiment is clearly advantageous in the case where the glass piece of the present invention is used as the front side of a screen. The antireflection layer according to the present invention may be, for example, a layer based on porous ceria having a low refractive index or it may be formed of several layers (stacks), in particular by alternating low refractive index and high refractive index layers and terminated by a low refractive index layer A stack of dielectric material layers is formed.

According to another embodiment, the glass sheet is coated with at least one anti-fingerprint layer to reduce/prevent the display of fingerprints. This embodiment is also advantageous in the case where the glass piece of the present invention is used as the front side of a touch screen. Such a layer can be combined with a transparent conductive layer deposited on the opposite side. Such a layer can be combined with an anti-reflective layer deposited on the same side, wherein the anti-fingerprint layer is on the outside of the stack and thus covers the anti-reflective layer.

The glass sheets according to the invention may also be treated on at least one of their major faces, for example using an acid or alkali de-lighting process to produce, for example, anti-fingerprint properties, or also to produce anti-glare or anti-glare properties. This is also advantageous especially in the case where the glass sheet of the invention is used as a touch-sensitive surface/screen.

Other layers/other treatments may be deposited on one side and/or the other side of the glass sheet according to the present invention, depending on the desired application and/or characteristics.

Furthermore, the invention relates to a screen or panel or panel comprising at least one glass sheet according to the invention, wherein the glass sheet defines a touch-sensitive surface. Preferably, the touch screen or the touch panel or the touch panel uses FTIR or PSD optical technology. In particular, the glass sheet is advantageously placed on top of the surface of the display.

Finally, the invention also relates to the use of glass flakes having a composition comprising the following materials, the content of which is expressed as a percentage of the total weight of the glass:

0.002 Total iron (expressed as Fe ₂ O ₃ ) 0.06%

It is used in devices that use infrared radiation that propagates primarily inside the sheet. It should be understood that the term radiation that propagates primarily within the sheet means radiation that travels between the two major faces of the sheet in the body of the sheet.

Advantageously, according to one embodiment of the use of the invention, the propagation of infrared radiation is performed by total internal reflection. According to this embodiment, infrared radiation can be emitted from one or more sides of the sheet within the glass sheet. The side of the sheet is understood to be defined by the thickness of the sheet and substantially perpendicular to each of the four major faces of the two major faces of the sheet. Alternatively, according to this embodiment, the infrared radiation may be emitted from the interior of the glass sheet at an angle from one or both of the major faces.

According to a particularly advantageous embodiment of the use according to the invention, the composition has for example 0.0005% Cr ₂ O ₃ 0.06% chromium content. Particularly preferably, the composition has such as 0.001% Cr ₂ O ₃ 0.06% chromium content. Even more preferably, the composition of the invention has, for example, 0.002% Cr ₂ O ₃ 0.06% chromium content.

According to an advantageous embodiment of the use according to the invention, the composition has a chromium content (expressed in the form of Cr ₂ O ₃ ) such as: 0.0001% Cr ₂ O ₃ 0.03%, or even better, such as 0.001% Cr ₂ O ₃ 0.03%, and more preferably, such as 0.002% Cr ₂ O ₃ 0.03%. These chromium content ranges enable significant transmission of infrared light and the aesthetic appearance of the glass sheet is not adversely affected. Even more preferably, the composition of the invention has a chromium content such as: 0.0001% Cr ₂ O ₃ 0.02%, or even better, such as 0.001% Cr ₂ O ₃ 0.02%, and preferably, such as 0.002% Cr ₂ O ₃ 0.02%.

According to another embodiment of the use of the invention, the composition has such as 55 SiO ₂ 78% of the SiO ₂ content expressed as a percentage of the total weight of the glass.

According to another embodiment of the use of the invention, which may be considered in combination with the preceding embodiments, the composition has such as 0 Al ₂ O ₃ 18% of the Al ₂ O ₃ content expressed as a percentage of the total weight of the glass.

According to a further embodiment of the use according to the invention, the composition advantageously has a total iron content (expressed in the form of Fe ₂ O ₃ ) of from 0.002% to 0.04% by weight, relative to the total weight of the glass, and preferably has a relative to glass Total weight, from 0.002% to 0.02% by weight of total iron content (expressed as Fe ₂ O ₃ ).

The following examples illustrate the invention and are not intended to limit its scope in any way.

Instance

The raw materials were mixed in powder form according to the composition specified in the table below and placed in a furnace.

The optical properties of the glass samples according to the invention in the form of flakes were determined and, in particular, determined at 1050 nm, 950 nm and 850 nm by transmission measurements on a Perkin Elmer lambda 950 spectrophotometer equipped with a 150 mm diameter integrating sphere. At the wavelength The absorption coefficient, the sample is placed at the entrance of the sphere for measurement. These same measurements were also made on reference (comparative) samples of the same base composition but without the addition of chromium.

The table below shows the absorption coefficients obtained for samples with chromium according to the invention and references at wavelengths of 1050 nm, 950 nm and 850 nm.

These results show that the addition of chromium in the content range according to the present invention enables a significant decrease in the absorption coefficient at the wavelengths of 1050 nm, 950 nm and 850 nm, and thus generally enables the absorption of near-infrared radiation to be reduced.

If the total amount of iron is less than the total amount of iron (e.g., 80 or 70 ppm) according to the examples of the present invention, the amount of chromium required to obtain the equivalent value of the absorption coefficient should be low. Conversely, if the total amount of iron is higher than the total amount of iron (for example, 130 or 150 ppm) according to the examples of the present invention, the amount of chromium required to obtain the equivalent value of the absorption coefficient should be high.

Claims (15)

A glass sheet having a composition comprising the following materials, the contents of which are expressed as a percentage of the total weight of the glass: 0.002 Total iron (expressed as Fe ₂ O ₃ ) 0.06%, characterized in that the composition contains, for example, 0.0001% Cr ₂ O ₃ 0.06% of the chromium content expressed as a percentage of the total weight of the glass. a glass sheet according to the preceding claim, wherein the composition has a 0.0005% Cr ₂ O ₃ 0.06% chromium content. a glass sheet according to the preceding claim, wherein the composition has, for example, 0.001% Cr ₂ O ₃ 0.06% chromium content. a glass sheet according to the preceding claim, wherein the composition has, for example, 0.002% Cr ₂ O ₃ 0.06% chromium content. A glass sheet according to any one of the preceding claims, wherein the composition has a total iron content (expressed as Fe ₂ O ₃ ) of from 0.002% to 0.04% by weight relative to the total weight of the glass. A glass sheet according to the above claim, wherein the composition has a total iron content (expressed as Fe ₂ O ₃ ) of from 0.002% to 0.02% by weight relative to the total weight of the glass. A glass sheet according to any of the preceding claims, wherein the composition has such as 55 SiO ₂ 78% of the SiO ₂ content expressed as a percentage of the total weight of the glass. A glass sheet according to any of the preceding claims, wherein the composition has such as 0 Al ₂ O ₃ 18% of the Al ₂ O ₃ content expressed as a percentage of the total weight of the glass. A glass sheet according to any of the preceding claims, wherein it has an absorption coefficient of less than or equal to 5 m ^-1 at a wavelength of 1050 nm. A glass sheet according to the above claim, wherein it has an absorption coefficient of less than or equal to 3.5 m ^-1 at a wavelength of 1050 nm. A glass sheet according to the above claim, wherein it has an absorption coefficient of less than or equal to 2 m ^-1 at a wavelength of 1050 nm. A screen or panel or panel comprising at least one glass sheet according to any one of claims 1 to 11, wherein the glass sheet defines a touch-sensitive surface. A screen or panel or panel as claimed in the preceding claims, which uses FTIR or PSD optics. A use of a glass sheet comprising a composition of the following materials, the content of which is expressed as a percentage of the total weight of the glass: 0.002 Total iron (expressed as Fe ₂ O ₃ ) 0.06%, the chromium content is such as: 0.0001% Cr ₂ O ₃ 0.06% is used in a device that uses infrared radiation that propagates primarily inside the sheet. The use of the aforementioned claim, wherein the propagation of the infrared radiation is performed by total internal reflection.